The research deals with the design of the so-called hierarchic multi-layers systems with the assumed final functionality utilized for microelectronics and/or photovoltaics. The individual components of such organization will be ordinarily formed from thin layers with highly ordered nano-particles, which ensure a partial function inevitable for the functionality of the whole system. The concrete arrangement primarily consists of titanium dioxide photoactive layer. Next, the surface of TiO
2 nano-particles are modified by a very thin film (several monolayers) of metal (gold or silver), eventually by a certain homogeneously distributed atomic aggregates of these metals in order to facilitate the transfer of electrons generated from TiO
2. The electron transfer can be alternatively enhanced using carbon nano-rods or nano-fibers. At the top of this two-component structure a layer of synthetic porphyrin or phthalocyanine (Pc) is placed with various types of central metal atoms. The role of the organometallic complex is to photochemically activate the semiconductor particles (TiO
2) in the visible light region of spectrum. Spectral properties of various phthalocyanine differ depending on the type of central metal, but the absorption maxima are always found in the area between 500 and 650 nm. However, already a marginal proportion of UV radiation, with wavelength shorter than 380 nm from the incident light, leads to the photochemical activation of titanium dioxide and subsequent degradation of the Pc. Therefore, Pc layer has to be protected by chemically passive, but physically active, transparent film composed of small particles of zinc oxide. It serves for the efficient separation of radiation with wavelengths shorter than 400 nm. Furthermore, whereas ZnO is a representative of so-called transparent conductive oxides, it also works as a conducting back electrode.
Carbon nanorods using for the electron transfer enhancement.
